Conventionally, a magnetic field generator for MRI receives complete adjustment of magnetic field intensity and magnetic field uniformity before shipment, and then transported to destination in a container for example.
However, despite such deliberate procedures, it sometimes happens that upon arrival, the magnetic field intensity has decreased, or the magnetic field uniformity has deteriorated down below an acceptable limit, and therefore readjustment must be made to the magnetic field generator.
This problem is particularly conspicuous in a magnetic field generator which makes use of magnetic flux leakage prevention magnets in order to reduce magnetic flux leakage and to concentrate magnetic flux from the main magnets to a center region. The problem is also conspicuous in exporting a magnetic field generator using a container, as well as in a magnetic field generator which has become popular recently in which a strong magnetic field (with a center magnetic field intensity being 0.25 T or greater) is generated for increased imaging speed.
It is therefore a primary object of the present invention to provide a magnetic field generator and a method of manufacturing it, capable of reducing the decline in the magnetic field intensity and the deterioration of magnetic field uniformity during transportation.